<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			// 'use strict'
			var a = 1;
			var obj = {
				a: 2
			}
			
			function test(){
				var a = 3;
				var b = 4;
				with(window){ //改变作用域
					console.log(a);
					console.log(b);
				}
			}
			
			test();
		</script>
	</body>
</html>
